This invention relates to a trigger-operated staple tacking device.
A known trigger-operated staple tacking device comprises a body and an operating handle which is pivotally connected at one end to the body, operation of the trigger to actuate a staple driving mechanism of the device being effected by squeezing the other end of the handle and the body together against the action of a return spring operative to return the handle to a position projecting from the body on release of the handle.
The staple driving mechanism of the known device comprises a cup-shaped striker block which is linearly moveable perpendicularly to an elongate staple-carrying element and which is biased into engagement with an anvil adjacent to the staple-carrying element by a helical compression spring extending in the direction of movement of the striker block. A staple driving blade is secured to the striker block so as to project beyond the anvil into a staple ejection slot adjacent to a supply end of the staple-carrying element. The operating handle is operatively connected to a rocker lever carrying a toe piece which engages in a recess of the striker block. When the handle is squeezed, the rocker lever pivots, causing the toe piece to move the striker block away from the anvil against the force of the helical compression spring. The staple driving blade is thereby retracted from the staple ejection slot, allowing a staple feeder in the staple-carrying element to introduce a staple into the ejection slot. Continued squeezing of the operating handle causes the toe piece to slip out of the recess in the striker block which is then driven forcibly back towards the anvil by the compression spring to cause the driving blade to eject the staple from the ejection slot.
In the known staple tacking device, the pivotally mounted handle of the device projects permanently from the body when the device is not in use.
Whilst this known device operates perfectly satisfactorily, the fact that the operating handle projects permanently from the body and the construction of the staple driving mechanism using a helical spring extending in the direction of movement of the striker block mean that the device is inconveniently shaped and rather bulky for some applications.